The generic term "scroll fluid device" is applied to the well-known arrangement of meshed, involute spiral wraps that are moved along curvilinear translation paths in orbiting fashion relative to each other to produce one or more fluid transporting or working chambers that move radially between inlet and outlet zones of the device. Such scroll devices may function as pumps, compressors, motors or expanders, depending upon their configuration, the drive system utilized and the nature of energy transferred between the scroll wraps and the fluid moving through the device.
Scroll devices, including their principle of operation, are fully described by way of example in U.S. Pat. Nos. 3,874,827 to Niels O. Yound; 3,560,119 to Busch et al.; and 4,141,677 to Weaver et al. The descriptions contained in the aforementioned patents, to the extent that they generally describe the theory of operation and typical structural arrangements of scroll fluid devices are herein incorporated by reference.
Scroll devices utilizing co-rotating scroll wraps are also generally known and provide certain advantages over scroll device utilizing a single orbiting scroll wrap and an opposed, cooperating fixed scroll wrap. In co-rotating scroll fluid devices, both scrolls rotate about laterally displaced parallel axes but are confined to relative orbital motion between themselves by means of suitable couplings, sometimes referred to as Oldham couplings. Oldham couplings are used in all types of scroll devices to prevent relative rotation between the meshed scroll wraps while permitting their relative orbital movement with respect to each other.
Co-rotating scroll devices provide the advantage that they can generally operate at a higher speed than single orbiting scrolls to minimize size and maximum operating efficiency. A typical example of a co-rotating scroll fluid device is illustrated in U.S. Pat. No. 4,178,143 to Thelen et al. In this example, a conventional Oldham coupling is used between the co-rotating scrolls to maintain them in fixed rotational relationship while permitting their relative orbital movement with respect to each other. A single driveshaft transmitting torque to one scroll wrap is illustrated, but it is also well known that both scroll wraps can be driven simultaneously in rotation.
Co-rotating scroll fluid devices known in the prior art and which provide an arrangement for unloading the sealing force between the flanks of the wraps are exemplified in U.S. Pat. No. 4,610,610 to Blain. Movement of one wrap of a co-rotating scroll fluid device relative to the other wrap to adjust the distance between the axes of the wraps while the device is operational is also suggested in the above-mentioned U.S. Pat. No. 4,178,143 to Thelen et al. Exemplary prior art describing lateral movement of the orbit center of a single orbiting wrap relative to a fixed wrap in a scroll fluid device is seen in U.S. Pat. No. 3,994,635 of McCullough, wherein a compliant drive system for the orbiting scroll is described. U.S. Pat. No. 4,795,323 issued Jan. 3, 1989 to Lessie illustrates an Oldham coupling comprising cooperating pins and circular grooves.
In a co-rotating as well as orbital scroll fluid device, a problem is encountered in the typical sliding ring-type Oldham coupling in that the sliding ring is subject to wear, vibration and adverse effects due to friction loading. Lubrication is usually required due to the friction between the sliding surfaces of the ring and high speed operation of a scroll fluid device may be limited by disturbances present between the sliding surfaces of this type of Oldham coupling.